<?php

class GTM_AMP_Css {
	private static $instance;

	public $name_hints = [
		// First loop replacement
		// Any specific class name
		[
			'gtm-has-block-flex-layout-' => 'gfl',
			'gtm-style'                  => 'gs',
		],

		// Second loop replacement
		// Any remaining class name
		[
			'gtm-has-block-' => 'ghb',
		],
	];

	public $css_vars = [];

	public static function get_instance() {
		if ( ! self::$instance ) {
			self::$instance = new self();
		}

		return self::$instance;
	}

	public function __construct() {
		if ( ! did_action( 'wp' ) ) {
			add_action( 'wp', [$this, 'init'] );
		} else {
			$this->init();
		}
	}

	public function init() {
		add_filter( 'print_styles_array', [$this, 'create_inline_styles'], 99 );
		add_filter( 'render_block', [$this, 'collect_block_hints'], 10, 2 );

		// Add hints for general css vars
		$this->add_css_var_hint( '--gtm-block-flex-layout-' );
		$this->add_css_var_hint( '--gtm-block-padding-' );
		$this->add_css_var_hint( '--gtm-block-margin-' );
		$this->add_css_var_hint( '--gtm--space--' );
		$this->add_css_var_hint( '--gtm--typography--' );

		// Allow adding custom name hints
		$this->name_hints = apply_filters( 'gtm_amp_css_compress_name_hints', $this->name_hints );
	}

	/**
	 * Move all gtm block styles to style tags for sanitizing later
	 */
	public function create_inline_styles( $handles ) {
		$wp_styles     = wp_styles();
		$final_handles = [];

		foreach ( $handles as $handle ) {
			$isGtmHandle = gtm_startsWith( $handle, 'gtm-' ) || gtm_startsWith( $handle, 'gutenmate-' );

			$url  = '';
			$file = '';

			if ( $wp_styles->registered[$handle]->src ) {
				$url  = $wp_styles->registered[$handle]->src;
				$file = gtm_url_to_local_path( $url );
			}

			if ( $isGtmHandle && ! empty( $file ) && file_exists( $file ) && is_readable( $file ) ) {
				$filetype = wp_check_filetype( $file, ['css' => 'text/css'] );

				// Allow only css files to be read
				if ( 'text/css' === $filetype['type'] ) {
					$content = gtm_get_file_content( $file );

					if ( $content ) {
						// Correct url()
						$parent_url = trailingslashit( dirname( $url ) );
						$content    = preg_replace( '|url\(\s*(["\']*)([^d\\\])|i', 'url($1' . $parent_url . '$2', $content );

						// Move to inline style
						$wp_styles->registered[$handle]->src = false;
						wp_add_inline_style( $handle, $content );
					}
				}
			}

			$final_handles[] = $handle;
		}

		return $final_handles;
	}

	public function compress_css_name( $style ) {
		if ( ! empty( $style ) ) {
			// Replace name from hints
			foreach ( $this->name_hints as $hints ) {
				$style = strtr( $style, $hints );
			}

			// Replace css vars
			foreach ( $this->css_vars as $hint ) {
				$style = str_replace( $hint[0], $hint[1], $style );
			}
		}

		return $style;
	}

	/**
	 * Generate prefix for new css name
	 */
	function get_prefix() {
		static $i = 1;
		return 'z' . base_convert( ++$i, 10, 36 );
	}

	/**
	 * Add hints for blocks
	 */
	public function collect_block_hints( $block_content, $block ) {
		if ( ! empty( $block['blockName'] ) ) {
			if ( gtm_startsWith( $block['blockName'], 'gtm/' ) ) {
				$pureBlockName = str_replace( 'gtm/', '', $block['blockName'] );
				$blockName     = str_replace( '/', '-', $block['blockName'] );

				$this->name_hints[1]['wp-block-' . $blockName]    = $this->get_prefix();
				$this->name_hints[1]['gtm-has-' . $pureBlockName] = $this->get_prefix();
				$this->name_hints[1]['is-style-' . $blockName]    = $this->get_prefix();

				$this->add_css_var_hint( '--' . $blockName . '-' );
			}
		}

		return $block_content;
	}

	public function add_css_var_hint( $name ) {
		$samePrefix = $this->get_prefix();
		$delimeters = [
			'(', '{', ';', '"', "'", ' ', "\t", "\n",
		];

		foreach ( $delimeters as $i => $char ) {
			$this->css_vars[$name . $i] = [$char . $name, $char . '--' . $samePrefix];
		}
	}
}